Re: How to handle secondary keys in partitioning?

[John Smith]

I didn't phrase my question very well.

I understand that MySQL will query each non-pruned partition automatically.

My question was more about how effective partitioning would be if some of my queries will involve all partitions.

So I partition my table into N partitions by recipient_id. And for some queries I want to "select * where sender_id=1 ordered by date".

For a non-partitioned table the above query would only require reading from 1 index, assuming I have an index on (sender_id, date). Also no sorting is required because the index is already sorted the right way.

For a partitioned table the same query would require reading from all N indexes and then sort the results, right?

For cases like that would partitioning actually reduce performance compared to a non-partitioned table? If so, what type of performance degradation would we will here?